The time when African-Americans were publicly hanged, burned and dismembered for insisting on their rights or for merely talking back to whites is nearer in history than many Americans understand. The horror of these crimes still weighs heavily on black communities in the South, where lynching memories are often vivid. The anguish is made worse by the realization that some of the killers are still alive and may never be prosecuted.

Consider Walton County, Ga., where the Justice Department is investigating the infamous Moore’s Ford Bridge lynching of 1946, in which a white mob tied up four black citizens — one of them pregnant — and shot them more than 60 times at close range. The killers were never brought to justice. The crime resurfaced three years ago when a white man in his 50s said in an interview with the N.A.A.C.P. that he had grown up hearing adults talking about the killings and that some of those responsible were still alive. He also said that the local police had ignored evidence that he had given them.

The Moore’s Ford Bridge case, often described as the last mass lynching in country, stands out for its wanton brutality and for the fact that one of its victims was George Dorsey, a World War II Army veteran who had recently returned to Georgia after serving five years in the Pacific. A study released last month by the Equal Justice Initiative, an organization that has been researching racial terror lynchings for several years, finds that black military veterans were disproportionately singled out for assault because Southerners viewed them as a particular threat to white supremacy.

This report adds to “Lynching in America,” a sweeping study of racial terror released by the organization last year. That study was based on a lengthy review of local newspapers, court records and historical archives as well as interviews with local historians, survivors and victims’ descendants. In the end, researchers counted 4,075 lynchings — about 800 more than have shown up in previous surveys. That so many killings were missing from the historical record illustrates the extent to which lynchings — sometimes carried out before hundreds of spectators — have been erased from public discourse.

The report about black veterans argues persuasively that former soldiers like Mr. Dorsey were targeted for assault because black men in uniform challenged the white supremacists’ idea of black inferiority and were seen as potential leaders in insurrections. Southern states reacted to this fear during the 19th century by making it a crime for African-Americans to own firearms.

Newspapers fanned the flames of hatred through sensational stories that portrayed black veterans as participants in a national “race war.” Local elected officials often worked hand in hand with the mobs, giving the public advance notice of these killings. By the time of the Moore’s Ford Bridge lynching, the report says, thousands of black veterans had been attacked, and many either narrowly escaped or were put to death by mobs.

Understanding the persecution that black veterans suffered from the Civil War period through World War II is crucial to understanding the nightmare of terror that extended to the Civil Rights Act of 1964, as well as the racism that pervades the country today. This report is especially relevant given that white supremacist groups with roots in the Jim Crow era have recently come marching out of shadows, emboldened by the poisonous rhetoric deployed in the Trump campaign.